Silencer



July' 5, 1960 J. JEFFORDS 2,943,695

SILENCER Filed Oct. 25, 1957 3 Sheets-Sheet l INVENTOR (lose vb I (laford;

ATTORNEY July 5, 1960 J. JEFFORDS 2,943,695

SILENCER Filed om. 2a, 1957 s Sheets-Sheet? ill-Ill I m1 INVENTOR doscp/v C/e/fqrcfs ATTORNEY J. JEFFORDS July 5, 1960 SILENCER 3 Sheets-Sheet3 Filed Oct. 23, 1957 -high compression gas United States Patent2,943,695 SILENCER Joseph Jefliords, 700 Park Ave., Baltimore, Md.

Filed Oct. 23, 1951, Sen. No.'691,863

3 Claims. 01. 181-50) The present invention relates to silencers forfluid exhausts whether they are of either pulsating or continuous flow.The silencer is constructed primarily for portable pneumatic-drivenapparatus, such as grinders, sanders, hammers, and the like. However, itmay be employed in any type of exhaust where a silencer would berequired or preferred whether portable or stationary.

One object of the invention is to provide a silencer that is compact andefficient and one that will reduce the to substantially atmosphericpressure.

Another object of the invention is to provide a disposable and soundabsorbing element which may be easily and quickly changed.

A further object is to provide an adjustable and removable air diif-userfor the silencer which will further diffuse the exhausted gases as theyare passed from the silencer and which may be utilized to hold the soundabsorbing and dissipating element in place'in the silencer.

A still further object of the invention is to provide means whereby thesound absorbing and dissipating element is surrounded by a resilientcushion for allowing slight movement thereof longitudinally and relativeto the outside housing of the silencer.

While several objects and uses of the invention have been set forth, itis not intended that they be conclusive, as other objects and uses maybecome apparent to those skilled in the art as its nature is more fullydisclosed.

The invention consists in its novel construction, combination and thearrangement of its several parts, all of which are illustrated in theaccompanying drawings and described in the description to follow.

Figure 1 is a sectional view of the silencer.

Figure 2 is an elevational view of the replaceable sound absorbing unitcarried by the silencer.

Figure 3 is a view of the silencer similar to that shown in Figure 1partly in elevation, the outer portion being broken away in order todisclose the sound absorbing and dissipating unit.

Figure 4 is a separate detailed view somewhat in plan of the sounddiffuser identified with the invention.

Figure 5 is a sectional view taken along the line 5-5 of Figure 3.

Figure 6 is a view in perspective showing the silencer in use with apneumatic grinden.

Figure-7 is a top plan view of the same. A

In referring to the drawings like numerals are used to point out likeand similar parts throughout the several views. 1

,Preferably,'the silencer has ajtapered or cone-shaped outer rigidhollow housing 10. This housing 10 is shown as being generally ofcylindrical form in cross-section, but it may have anydesirable'conventional cross-sectional shape, such as square,rectangular, etc. Also, the housing may increase its diameter in stepsrather than being tapered, if desired.

The small end 10' of the housing. 10 is provided with an air intakeopening 12 adapted to engage the exhaust end of the apparatus or forconnecting it with an exhaust conduit. One means for accomplishing thisis by a threaded coupling 12'. The larger end 10 of the housing 10 isprovided with an opening 19 having a diameter at least twice the size ofthe air intake opening 12 on the opposite end of the housing justdescribed. Surrounding the outer edge of the larger end 10" is a fixedring 14. Over the larger end 10" of the housing 10 and the fixed ring 14is a sound ditfuser D which is provided with an outer casing 20 havingan inner side 20' adapted to be secured to the housing. The side is funther provided with a circumferential flanged portion 20 adapted toslidably fit over the ring 14. On the side 20 of the difiuser casing 20there is an opening 22 at least as large as the opening 19 leading fromthe larger end 10" of the housing. In the portion 20" is a plurality ofthreaded holes 20" so spaced about its circumference as to threadablyreceive screws 18. Adapted to slidably engage the inner surface of thering 14 is a second ring '16. The ring 16 is provided with a number ofspaced apertures adapted to slidably receive screws 18 which are alsoopposite the threaded holes 20". By this arrangement the diffuser 20 maybe adjusted about the axis of the housing and fixed in any desiredposition by tightening down on the screws 18, or the degree of tightnessof the screws may be sufficient to enable the turning of the difiuser toany desired position and maintained in said position without additonaltightening of the screws. The diffuser is provided with an opening 23which is at ninety degrees with the opening 22. The area of the opening23 is at least as large as the opening 22.

Over the outer opening of the diifuser 20 is a perforated plate 24. Theperforations are in the form of openings 25. The total area of theopening 25 is also at least as great as the area of the openings 19 and22 in the larger end 10f of the housing 10.

In the operation of most apparatus by compressed air, there are alwayssmall amounts of oil, dirt and the like 7 being discharged, and theordinary silencer soon becomes clogged with this oil, dirt, etc., whichis prone to get on the operator, or the work, or both, and it is thepurpose gularly disposed to each other, the angles of the portions 30and 30' of the side walls being in separate planes substantially atright angles to each other and are joined along both their respectiveinner and outer edges. The :wall sections 30 are angled to face towardsthe inlet end of the silencer and are provided with a plurality ofopenings 32. The inner wall surface of the member A consists of aplurality of hills 34and valleys 36 sloping from the outer'perimeterangularly toward the inner apex centerwise. On the outside of the sidewalls and within the recesses oppositethe inner hills 34 there'isprovided a relatively loosely packed mass of'g'lass fibers- 39, usuallyreferred to as .fiber glass, or other suitable and availableinterstitial material,which extends out-' wardly to a line drawn betweenthe lower points of'the inner valleys 36. About the glass fibers 39there is a felt wrapping 38, or other suitable fibrous non-soundconducting material.

The elements A, 38 and 39 go to make up the sound absorbing anddissipating insert unit.

The sound-" absorbing element A may hesecured to each end of'thecovering 38 for keeping. the element. in. full. extended position, thesmall end of the. element A being secured to the covering 38 at 42, andthe larger end being secured to the cover38r at. 44;. Thissound-absorbing and-dissipating'dispcs able element is'zadapted to beinsertediwithinl the larger endlof the housing 10 and to fit snuglytherein", andz is: held in.- place positionallyi by any conventional?means onlack oi displacement space. In.the pre'sent dis'- closure thesound-absorbing: unit: is shown held within the: housing by thegas-diffusing:memberztllwhich has herein before-been described: asadjustably securedto. the larger end of the silencer.

Within the diffuser D there isprovided an inner cover ing 21 of a;material: having a minimum amount: ofsound transmitting qualities;-suchas fiber glass, papier-mache', felt, or other interstitial material;

The bellows shaped sound-absorbing and dissipating ele'mentiA; with its:angledside portions 30" and 30 ex tends the full length of the silencerhousing It The member A; is tapered outwardly in the same proportionsasthehousing 10 as" it approachesthe outlet endof the housing. The memberA is-fo'rmed of a non-sound transmitting material and is preferablymolded from papier-- mache, plastic, or similar interstitial material.

The air inlet 12 to the housing, as stated before, ispreferably ofsubstantially at least one-half the diameter of the' outlet opening 19in the housing. It willbe noted that thesound-absorbing' element A- isof a structure that has a plurality of connecting sound receptacles inwhich the 'Wallportions 30' and rneet each other at right angles. Thistype structure also lends itself to a slight oscillation lengthwise ofits long axis of the housing-pant icularly when its opposite ends areheld substantially at fixed points. The openings 32 in the wall portion30' also act to allow the air pressure to be evenly distributed onthe'inner and outer surfaces of the wall sections 30 and'30' to preventcollapse and distortion of the walls.

In using the silencerwith some types of tools; or apparatus, a handle 4%is provided to aid in'manipulating. and balancing the tool. However,.thehousing may very well'be used. for ahandle itself.

The silencer is' 'illustrate'd in use with a grinding tool as shownin'Figures 7' and 8. These grinding tools comprise generally a rotatablearbor (not shown) carried within a casing 52' on which issecured agrindingwheel 56; Compressed air i'sled into the casing by the flexibleconduit 58 and exhausted through an opening 60" which is connected withthe threaded connector 12' of the silencer. The flexible conduit 58 isin turn secured to a rigid conduit 61'. Associated with this rigidportion 61 is an air valve control lever 62. This rigid conduit 61serves as a guiding. and manipulating handle for the apparatus;

In operation, compressedair is fed into the casing. 52 which rotates thearbor and the grinding wheel 56 by the principle ofturbine propelledfins. (not shown). The air is exhausted out of the opening 6%) into'thesmall inlet 12 at the small end of the silencer. As the air movesthrough the silencer, it expandscontacting with. force the sides 30 ofthe. member A in particular, which. is angled toward thev oil-comingair. Fart of}? the air. and sound passes through the openings 32 intothe fiber glass 39 and is cushionedthereby whichlalsobuilds up apressure. onthe outside of the walllportions 30 and '30.'.. The soundcon tacting thesurfacesfitl and 30. is'rebounded atsright angles to.eachother, and, therefore, the, sound. is. disrupted and. silenced. bythe-principle of losing sound valusby chang.-. ingthesonnd wavedirection'. The': member'A, beginning.

at its smaller end, gradually increases in cross-scctional area towardthe: larger end of the housing and the outlet end of the silencer which,in turn, increases the size of the connected sound receptacles. Thisallows the compressed air to expand" progressively and to return quite 4nearly to normal atmospheric extent. dissipate the. sound.

When the air and sound enter the air diffuser 20, the direction of thesound and air are again changed at an angle of approximately 90 degrees,which change in direction further dissipates the sound. The sound isstill further reduced by passing the exhaust air from the difiuseroutwardly throughthe plurality of openings 25 at the outer end of theditfi'lser.

The silencer is not onlyazla titerl to use on such apparatus as showninsFigures 7 and 8,. but may be used in many other types oftbols' orapparatus such as previously referred to, and other instances toonumerous to pressure, and to a large mention.

The location of the silencer on the apparatus is important. It islocated at a point not more than degrees from the air intake and handlemember in order to provide a second handle at a convenient location andto make the? apparatus the more maneuverableand available to work intoclose places? particularly in corners of. various structures. Theposition: of the diffuser is adjustable to directth'e exhaust. gasestoward the work, or: the apparatus may: be moved-into suchapositionover; the work asto. remove or. blow objectionableabrasives,=.grindings-, etc; from the work surface.

While the invention has been: illustrated and described in. aparticular. form, it is not intendedas. a limitation and its scope is:best defined in the appended claims which have been allowed in view ofthe prior art.

l. A. silencer for absorbing. and dissipating: the sound of highpressure exhaust gases from fluidactuatcd apparatus comprising, meansfor attaching the silencer to he said apparatus, the silencer having anouter elongate rigid continuous-side wall and a. gas inlet opening atone enclfor receiving the high pressure gases and-a out let opening inthe opposite end of the housing from which the gases are'exhausted fromthe silencer under low pressure to the atmosphere, the housing being. ofsmaller di ameter at the end. of the housing adjacent the gas inletopening of larger diameter at the end adjacent: the gas outlet opening,the housing increasing progressively in. diameter: from 'the' endadjacent. the: inlet opening, to the end adjacent: the outlet opening.for gradually; increasing the cubic area: of the housing to providespace for the expanding gases as their. pressure: is lowered, anelongated separate insertable disposable. inner element of substantiallythe same length and: adjacent. the. inside surfaceofthe housing andform-fittingwith.respectatosaid housing surface, said insertableelementhaving an conitinuous bellows shapediside wall inwhichthalfi of theinner surfaces of the bellows. Wall areangled toward: the gas inlet andthe other half are: angled toward the. gas outletprov-iding a pluralityof communicating sound' receptacle therein, the diameter of the bellowsinsert in-- creasingin diameterfrom the gas intake end of the silencerto the gas outlet end thereof, a resilient cushion surrounding thebellows w-all element andrncans removably engageable with the exhaustend of the silencer housing for. retaining the same within the housing.

2. A silencer for absorbing and dissipating the. sound of. high pressureexhaust. gases from fiuidactuated apparatus comprising, means. for.attaching the silencer to the said, apparatus. the silencer having an.outereiongated rigid continuous?sidevwalliand a. gas inlet openingatoneendtifor:recciving'thehigh pressure; gases. anda gas! out let opening inthe opposite end of thehousing from'rwhich the gases are exhausted-fromthe silencer under low-pressure to the atmosphere; the housing being ofsmaller diatncter at the end of the'housing adjacent the gas inletopening and of larger diameter at the and adjacent the gas outletopening, the housing increasing progressively indi'ameter 'from the endadjacent the-inlet'opening to the end adjacent the outlet opening forgradually increasing the cubicarea of the housing'to providespace-for'the-en panding gases as their pressure is lowered, an innerelement Within the housing having a central passage increasing indiameter in the same ratio as the outer housing extending therethrough,the walls of the inner element having a plurality of rigid angledsurfaces positioned substantially at right angles to each otherextending about the inner element and increasing in area progressivelyfrom the small to the large diameter of the element for engaging part ofthe gas stream passing through the central opening for changing thedirection of that part of the gas stream and directing the same backinto the remaining portion of the gas stream passing through the centralopening, a low sound conducting wrapping extending about the innerelement adapted to fit into the said outer housing, a gas diffuserfitted to the large exhaust end of the housing having an inlet at leastequal in size to the gas outlet of the inner element and an outlet inthe storm of a plurality of small openings of which their total areasare at least equal to the area of the diituser intake opening 3. In adevice as claimed in claim 2 in which the sound absorbing element isprovided with a plurality of openings on the surfaces of the bellowselement angled toward the gas inlet opening for admitting air and soundwaves beyond the bellows surfaces for equalizing the pressure on eachside of the bellows surface to prevent its collapsing under the highpressure of the exhaust gases.

References Cited in the file of this patent UNITED STATES PATENTS1,115,704 Manes Nov. 3, 1914 1,162,064 Hutton Nov. 30, 1915 1,442,196Truelson Jan. 16, 1923 2,073,480 Jimerson Mar. 9, 1937 2,154,133Mcllvaine Apr. 11, 1939 2,166,218 Morrison July 18, 1939 2,206,259 Nieldet al. July 2, 1940 2,342,905 Smellie -1 Feb. 29, 1944 2,561,726 CherainJuly 24, 1951 2,643,731 Schmid June 30, 1953 FOREIGN PATENTS 704,741France Feb. 24, 1931 287,597 Italy July-28, 1931 563,110 Great BritainJuly 31, 1944 553,321 Italy Dec. 22, 1956

